A common cooking process involves immersing food to be cooked in a heated fluid, most commonly water, oil or steam. One form of this cooking process is blanching, for example, which typically refers to the immersion of the food in heated water and is a common technique for partially cooking, among other things, vegetables prior to freezing or canning. Blanching is conventionally used as a form of precooking to inactivate or arrest enzymes from attacking a food to cause it to discolor, become changed in texture, or lose flavor. Blanching softens some foods, like asparagus and decreases the volume of foods like spinach, thus permitting proper packaging. Blanching is also used for fruits and vegetables to remove the off-flavors, expel the occluded air, set the color, improve the texture, and cleanse the product.
With potatoes, for example, blanching destroys enzyme activity, leaches out reducing sugars that can cause discoloration, and improves texture. Proper blanching, however, requires that the food be cooked to a particular level of doneness. Accurately determining the proper doneness level is difficult, however, since for a given type of food the size, moisture content, consistency, and shape can all contribute to the time required for the cooking process. Again with potatoes, for example, characteristics such as sugar content can vary with cultivar, growing conditions and storage environment, thereby increasing the complexity of determining the desired level of doneness during the blanching operation.
Unfortunately, the ability to rapidly, reliably, and efficiently monitor the degree of cooking of foods in a non-invasive manner without the need for constant monitoring by trained individuals is limited. Accordingly, it is an object of the present invention to provide improved systems and techniques for monitoring cooking using ultrasonic techniques that increase the degree of automation and thereby reduces costs.